#include <stdio.h>
        #include <stdlib.h>

        main(argc, argv)
            int argc;
            char *argv[];
        {
            FILE *fp;

            fp = fopen(argv[1], "r");   /* Open an input file. */
            if (fp == NULL) {

                /* If the fopen call failed, perror prints out a        */
                /* diagnostic:                                          */
                /*                                                      */
                /*  "open: <error message>"                             */
                /*  This error message provides a diagnostic explaining */
                /*  the cause of the failure.                           */

                perror("open");
                exit(EXIT_FAILURE);
            }
            else
                fclose(fd) ;
        }